1. Field of the Invention
This invention relates to catheters and catheter assemblies for use in medical procedures. More specifically, the present invention is directed to catheter assemblies for use in treating stenoses at one or more vessel bifurcations.
2. Description of the Related Art
Percutaneous transluminal coronary angioplasty (PTCA) is a procedure which is well established for the treatment of blockages in the coronary arteries. Blockages may occur from cholesterol precipitation on the coronary wall which may be in any stage from initial deposit through aged lesions. Coronary arteries may also become blocked due to formation of thrombus.
The most widely used form of percutaneous coronary angioplasty makes use of a dilatation balloon catheter which is introduced into and advanced through a lumen or body vessel until the distal end thereof is at a desired location in the vasculature. Once in position across a lesion site, the expandable portion of the catheter, or balloon, is inflated to a predetermined size with a fluid at relatively high pressures, to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile so that the dilatation catheter may be withdrawn from the patient's vasculature and blood flow resumed through the dilated artery.
In angioplasty procedures of the kind described above, there may be restenosis of the artery, which either necessitates another angioplasty procedure, a surgical by-pass operation, or some method of repairing or strengthening the area. To reduce restenosis and strengthen the area, a physician can implant an intravascular prosthesis for maintaining vascular patency, such as a stent, inside the artery at the lesion.
Stents, grafts, stent-grafts, vena cava filters and similar implantable medical devices, collectively referred to hereinafter as stents, are radially expandable endoprostheses which are typically intravascular implants capable of being implanted transluminally and enlarged radially after being introduced percutaneously. Stents may be implanted in a variety of body lumens or vessels such as within the vascular system, urinary tracts, bile ducts, etc. Stents may be used to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. They may be self-expanding, such as a nitinol shape memory stent, mechanically expandable, such as a balloon expandable stent, or hybrid expandable.
Some stents have been developed specifically to address the problems that arise in the treatment of stenoses at or near the site of a bifurcation of a body lumen are known in the art. Further, single bifurcated stents and grafts have been developed in order to treat such conditions at the site of a branch of a body lumen. A bifurcated stent and/or graft typically is configured in a “pant” design which comprises a tubular body or trunk and two tubular legs, however other configurations are also known wherein the stent includes a plurality of separate and/or inter-connectable portions which may be delivered to various positions at or around the bifurcation using a single or multiple catheters. Some examples of bifurcated stents are shown in U.S. Pat. No. 5,723,004; U.S. Pat. No. 4,994,071; and U.S. Pat. No. 5,755,735.
Prior to delivery a stent or stents may be retained on a portion of the delivery catheter by crimping the stent onto the catheter, retaining the stent in a reduced state about the catheter with a removable sheath, sleeve, sock or other member or members, or by any of a variety of retaining mechanisms or methods. Some examples of stent retaining mechanisms are described in U.S. Pat. No. 5,681,345; U.S. Pat. No. 5,788,707; U.S. Pat. No. 6,066,155; U.S. Pat. No. 6,096,045; U.S. Pat. No. 6,221,097; U.S. Pat. No. 6,331,186; U.S. Pat. No. 6,342,066; U.S. Pat. No. 6,350,277; U.S. Pat. No. 6,443,880; and U.S. Pat. No. 6,478,814.
Various techniques have been used to deliver bifurcated stents in order to provide radial support to both a main blood vessel, and contemporaneously to side branches of the blood vessel. Examples of catheters for use in treating bifurcated lumens or delivery systems for bifurcated stents, are shown in U.S. Pat. No. 5,720,735; U.S. Pat. No. 5,669,924; U.S. Pat. No. 5,749,825; U.S. Pat. No. 5,718,724; and U.S. Pat. No. 6,129,738. As maybe seen from these references, in many bifurcated stent delivery systems, the bifurcated stent is mounted on a catheter assembly which comprises essentially two balloon catheters mounted in a guide catheter assembly.
Providing a bifurcated catheter, and particularly providing the secondary portion of the catheter with proper radial alignment and sufficient flexibility to be readily advanced and positioned into the side branch of the bifurcation is a significant issue with many bifurcated catheter assemblies. Another issue which exists in some bifurcated catheter assemblies for use in delivering a bifurcated pant design stent is that retention systems for retaining the side component of the stent contribute undesirably to the diameter of the catheter and may inadequately retain and/or improperly retract from one or more ends of the stent branches or legs prior to and/or during delivery.
The present invention seeks to address these problems by providing catheter assemblies with a variety of embodiments and features which improve catheter performance and side branch accessibility.
All US patents, applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.